Screw thread lapping device



Nov. 30, 1943. 7 A. M. DRAKE SCREW THREAD LAPPING DEVICE Filed Nov. 2'7, 194]. 3 Sheets-Sheet 1 SCREW THREAD LAPPING DEVICE Filed Nov. 27, 1941 3 Sheets-Sheet 2 g INVENTOR I AldenMDra/I'e ATTORNEY Nov. 30, 1943. A. M. DRAKE 2,335,745

SCREW THREAD LAPPING DEVICE I Filed' Nov. 27, 1941 3 Sheets-Sheet 3 INVENTOR Zldmzkfirake Patented Nov. 30, 1943 SCREW THREAD LAPPDIG DEVICE Alden M. Drake, West Hartford, Conn., assignor to Niles-Bement-Pond Company, West Hartford, Conn, a corporation of New Jersey Application November 2'7, 1941, Serial No. 420,637

4 Claims.

This invention relates to mechanical lapping devices and particularly to a device for lapping internally threaded ring gages,

A primary object of the invention is to provide a simple and efficient mechanical lapping device particularly adapted for lapping or abrading taper thread ring gages enabling the threaded portion of the gage to be finished to a predetermined dimension and have an extremely smooth gaging surface.

A feature that enables me to accomplish the above named object is that the lap is mounted for rotation upon its axis back and forth through fractional parts of a revolution and that the gage being lapped is oscillated back and forth over the lap in timed relation to but in opposed directions of rotation relative to the rotation of the lap.

Another object of the invention is to provide means for slightly varying the position of the gage being lapped axially along the threaded portion of the lap so that successively larger diameters of the lap may be contacted with the gage as the lapping operation progresses.

And finally it is an object of the invention to limit the swinging movement of the gage being lapped positively in one direction and limit the swinging movement in the other direction by resiliently yielding means so that the swinging member may have a slight additional ro-tative movement after the gage has taken up tightly upon the threaded portion of the lap, and so that the gage will be resiliently advanced upon the lap but positively released therefrom by movement of the swinging member in the opposite direction.

With the above and other objects in view the invention includes the features of construction and operation set forth in the following specification and illustrated in the accompanying drawmgs.

In the accompanying drawings annexed hereto and forming a part of 'this specification, .I have shown the invention embodied in a single spindle device forming one part of a lapping device for taper threaded ring gages, but it will be understood that the invention can be otherwise embodied and that the drawings are not to be construed as defining or limiting the scope of the invention, the claims appended to this specification being relied upon for that purpose.

In the drawings:

Figure 1 is a side elevation of a lapping device made according to the present invention, parts being shown in section to more clearly show their construction.

Fig. 2 is a front elevation of the device shown in Fig. 1, partly in section, the swinging member for actuating the gage being lapped being shown in different operative positions.

Fig. 3 is a vertical sectional view taken on the line 33 of Fig. 1.

Fig. 4 is a front view partly in section of the head slidably carried by the swinging member for connecting and operating the arm mounted on the gage holder, and

Fig. 5 is a plan view of the head shown in Fig. 4.

In the above mentioned drawings there has been shown but one embodiment of the invention which is now deemed preferable, but it is to be understood that changes and modifications may be made within the scope of the appended claims without departing from the spirit of the invention.

Briefly and in its preferred aspect, the invention may include the following principal parts: First, a spindle mounted within a suitable base and having means to rotate it back and forth through limited arcs; second, a lap attached to one end of the spindle for rotation therewith upon its axis; third, a swinging member mounted upon suitable bearings within the base and preferably geared to and rotating relative to the spindle but in opposite directions thereto; fourth, a plunger mounted within the swinging member for engagement with different teeth of a gear rotating with this swinging member; fifth, a rod extending from the swinging member in a direction parallel to the spindle; sixth, a gage holding member having an arm outstanding therefrom; and seventh, a connecting member or head slidably fitting over the rod extending from the swinging member and bearing against opposite sides of the arm on the holding member, there being a flexible and resilient portion on said head which bears against one side of said arm.

Referring more in detail to the figures of the drawings, I provide a base or support It! for a spindle I I mounted for rotation therein and having a chuck or other attaching means 52 at one end. Fitting within this chuck I2 is a lap l3, the one shown being of taper threaded form. The chuck shown in the drawings is of the frictional collet type enabling the lap I3 to be readily positioned adjustably on the spindle H at any rotative angle and removed therefrom for substitution of laps of different types and sizes. Means are provided such as an arm l4 extending from the spindle ll connected to a crank l5 on driving shaft [6 by means of connecting rod I! for rotating the spindle ll back and forth through limited arcs.

Mounted on the spindle H adjacent one end is a gear member i3 meshing with a smaller gear 19 mounted on a shaft 2?] preferably above and eXtending parallelly to the spindle II. It will be seen from this construction that angular movements back and forth of the spindle II will correspondingly swing the shaft 28 through an arc substantially greater than that of the spindle. On the forward end of this shaft 20 is secured a toothed member 2! housed within a swinging member 22 supported upon the shaft. On the outer or free end of this swinging member 22 is a bearing through which extends a rod 23 disposed in a direction parallel to the shaft 29 and spindle ll.

Within the swinging member 22 is a plunger 2 the inner end of which engages the toothed member on the shaft. By manually withdrawing the plunger radially a short distance to disengage it from the toothed member 2| the ang gular position of the swinging member 22 relative to the shaft 252 may be slightly varied.

The gage W to be lapped is mounted within a holder 25 shown clearly in Figs. 1 and 2 which comprises a strap portion surrounding the outer diameter of the gage W and is adapted to be clamped about the periphery of the gage. This holder 25 also has an arm 26 extending radially therefrom, as will be seen by reference to the above referred to figures.

Mounted on the rod 23 carried by the swinging member 22 is a connecting member or head 2? slidable thereon for contacting the gage holder arm. This member or head 27 is freely slidable along the rod outstanding from the swinging member and contacts the gage holder arm 25 against one side and within a slot or recess formed by side flanges on the member 21. This member or head 22 also carries a smail head 28 engaging the opposite side of the gage holder arm 26, the head 28 being resiliently attached to the member 2? as by the metal strip spring 23 bent as shown in Fig. l.

In operation the driving shaft i6 is rotated, which oscillates the arm Hi provided on the spindle i E and thus rotates the spindle through limited angular distances in opposite directions. This rotation, in turn, through the gear connections provided therefor, causes angular movements in opposite directions of the swinging member 22 connected flexibly to the arm 26 extending from the gage holder by means of the rod 23 and the head 27. The swinging member .22 and arm 2% therefore cause swinging movements back and forth of the gage W and its holder 25 over a small part of the threaded portion of the lap 83. During the lapping operations on the gage as the size of the lapper threads increases slightly the gage W and its holder 25 may be advanced axially along the lap l3 by withdrawing the end of the plunger 2 from the toothed member 2! and re-engaging its inner end within an adjacent tooth of the tooth member on the shaft 26. In one direction of oscillation of the swinging member 22 and its rod 23 the arm 25 will bear directly against the head 21 slidable along the rod 23. In the opposite direction of movement of the swinging member 22 the arm will bear against the head 28 which is, as shown, flexibly connected to the head member 2'3. In the direction of movement of the swinging member 22 that advances the gage W toward the increased diameter of the lap It) the arm 26 bears against the flexibly mounted head 28 so that the swinging member 22 can complete its oscillatory movement after the gage W tightly engages the threads of the lap I3. In the opposite direction of oscillation of the swinging member 22 the arm 26 bears against the head 21 and the gage W is therefore positively released from the lap l3 and rotated toward the reduced diameter portion of the lap I3.

What I claim is:

1. A lapping device for thread ring gages comprising in combination, a threaded lap member mounted for rotation upon its axis, means to r0- tate the lap through limited angular distances in opposite directions, a swinging member actuated in timed relation to and in opposite directions to the rotative movements of said lap, and a gage holder retaining a gage being lapped in position upon said lap, said holder having an arm outstanding therefrom, a head on said swinging member bearing against one side of said arm, and a resiliently mounted member on said head bearing against the opposite side of said arm, whereby rotative movements of said lap will rotate said gage being lapped over the threaded portion of said lap.

2. A lapping device for thread ring gages coinrising in combination, a threaded lap member mounted for rotation upon its axis, means to rotate the lap through limited angular distances in opposite directions, a swinging member actuated in timed reiation to the rotative movements of said lap, a head slidable on said swinging member, and a gage holder retaining a gage being lapped in position upon said lap, said holder having an arm outstanding therefrom and contacting the head on said swinging member, whereby rotative movements of said lap will rotate said gage being lapped over the threaded portion of said lap.

3. A lapping device for thread ring gages comprising in combination, a threaded lap member mounted for rotation upon its axis, means to rotate the lap through limited angular distances in opposite directions, a swinging member actuated in timed relation to the rotative movements of said lap, a head slidable on said swinging member having a resiliently mounted abutment thereon, and a gage holder retaining a gage being lapped in position upon said lap, said holder having an arm engaging said head on said swinging member, whereby rotative movements of said lap in one direction will positively rotate said gage being lapped over the threaded portion of said lap, and rotation of the lap in the opposite direction will resiliently rotate said gage over said lap.

i. A lapping device for taper thread ring gages comprising in combination, a threaded lap member mounted for rotation upon its axis, means to rotate the lap through limited angular distances in opposite directions, a swinging member actuated in timed relation to the rotative movements of said lap, a head slidable on said swinging member having a resiliently mounted abutment thereon, and a gage holder retaining a gage being lapped in position upon said lap, said holder having an arm engaging said head on said swinging member, whereby rotative movements of said lap in one dir ction will resiliently advance the gage along the lap to portions of increased diameter,

and in the opposite direction will positively rotate the gage in the opposite direction.

ALDEN M. DRAKE. 

